I always use concrete.
Maybe if I tamped down the soil with a 2x4 pushrod and a sledge hammer I could get away with only soil but it seems to me that with only soil the rest of the fence is holding each post vertical rather than the post base.

I always use concrete.
Maybe if I tamped down the soil with a 2x4 pushrod and a sledge hammer I could get away with only soil but it seems to me that with only soil the rest of the fence is holding each post vertical rather than the post base.

What do you think is holding your post with a lump of concrete on it?
I have seen a fence blown over with a good wind, concrete and all, the soil was saturated , almost mud.